docs: def _process_human_orthos(self, limit=None):
          """
          This table provides ortholog mappings between zebrafish and humans.
          ZFIN has their own process of creating orthology mappings,
          that we take in addition to other orthology-calling sources
          (like PANTHER). We ignore the omim ids, and only use the gene_id.
  
          Triples created:
          <zfin gene id> a class
          <zfin gene id> rdfs:label gene_symbol
          <zfin gene id> dc:description gene_name
  
          <human gene id> a class
          <human gene id> rdfs:label gene_symbol
          <human gene id> dc:description gene_name
          <human gene id> equivalent class <omim id>
  
          <zfin gene id> orthology association <human gene id>
          :param limit:
          :return:
  
          """
  
          if self.test_mode:
              graph = self.testgraph
          else:
              graph = self.graph
  
          LOG.info("Processing human orthos")
          line_counter = 0
          geno = Genotype(graph)
          # model = Model(graph)  # unused
          raw = '/'.join((self.rawdir, self.files['human_orthos']['file']))
          with open(raw, 'r', encoding="iso-8859-1") as csvfile:
              filereader = csv.reader(csvfile, delimiter='\t', quotechar='\"')
              for row in filereader:
                  line_counter += 1
                  (zfin_id, zfin_symbol, zfin_name, human_symbol, human_name,
                   omim_id, gene_id, hgnc_id, evidence_code, pub_id
                   # , empty
                  ) = row
                  if self.test_mode and zfin_id not in self.test_ids['gene']:
                      continue
  
                  # Add the zebrafish gene.
                  zfin_id = 'ZFIN:' + zfin_id.strip()
                  geno.addGene(zfin_id, zfin_symbol, None, zfin_name)
  
                  # Add the human gene.
                  gene_id = 'NCBIGene:' + gene_id.strip()
                  geno.addGene(gene_id, human_symbol, None, human_name)
  
                  # make the association
                  assoc = OrthologyAssoc(graph, self.name, zfin_id, gene_id)
                  # we don't know anything about the orthology type,
                  # so we just use the default
  
                  if re.match(r'ZDB', pub_id):
                      assoc.add_source('ZFIN:'+pub_id)
  
                  eco_id = self.get_orthology_evidence_code(evidence_code)
                  if eco_id is not None:
                      assoc.add_evidence(eco_id)
  
                  assoc.add_association_to_graph()
  
                  if not self.test_mode and limit is not None and line_counter > limit:
                      break
  
          LOG.info("Done with human orthos")
          return